Electrical switch



Oct. 15, 1957 o. HERRMANN ETAL 2,810,035

ELECTRICAL SWITCH Filed nay 5. 1955 2 sheets-sheet 1 'f f? al 5a Oct. 15, 1957 o. HERRMANN Er A1.

ELECTRICAL SWITCH 2 Sheets-Sheet 2 Filed May 5. 1955 lll/11111712 w m W. w

@We Heyrmmn CM Kuur* QCML Unite States Patent ELECTRICAL SWITCH Otto Herrmann, Stuttgart, and Kurt Paule, Stuttgart- Oberturkheim, Germany, assignors to Robert Bosch G. m. b. H., Stuttgart, Germany Application May 5, 1955, Serial No. 506,248

Claims priority, application Germany May 28, 1954 Claims. (Cl. 200-83) The present invention relates to an electrical switching arrangement. More particularly the present invention relates to a new and improved snap-acting electrical switch.

It is an object of the present invention to provide a new and improved electrical switching arrangement.

Another object of the present invention is to provide a new and improved snap-acting electrical switch.

A further object of the present invention is to provide a compact and inexpensive electrical switch capable of carrying substantially high current loads.

Still a further object of the present invention is to provide a pressure actuated snap-acting electrical switch.

With the above objects in view, the present invention relates to an electrical switching arrangement including a housing, a double-armed toggle member pivotally mounted in the housing at a point between the arms thereof and turnable between two positions, a switch member movable between open and closed conditions and operatively connected to a toggle arm of the toggle member so as to be in one of the conditions when the toggle member is in one of the positions and to be in the other of the conditions when the toggle member is in the other of the positions, operating means engaging one of the toggle arms of the toggle member for turning the same from one of the positions to the other position thereof, and spring means engaging the other of the toggle arms of the toggle member and permanently tending to turn the same toward one position thereof.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of speciiic embodiments when read in connection with the accompanying drawings, in which:

Fig. l is a transverse sectional view of one embodiment of the apparatus taken along the line I-l of Fig. 2;

Fig. 2 is a plan View of the apparatus with the cover removed and some of the parts shown partially in section;

Fig. 3 is a sectional view taken along the line IIL-III of Fig. 2;

Fig. 4 is a perspective view of la double-armed toggle member used in a preferred embodiment of the apparatus; and

Fig. 5 is an exploded View of the apparatus showing how the various elements are arranged in the housing.

Referring to the drawings and more particularly to Fig. 5 it can be seen that the apparatus is contained in a housing having a U-shaped portion with facing side walls 51 and 52. The edges of the side walls are substantially parallel to each other and have rounded portions 54. Slidably cooperating with the side walls 51 and 52 are the two remaining side Walls and 56 which have rounded tabs 57 at their edges for gripping the adjacent ice side walls so that the side Walls of the housing are interlocked.

Completing the housing is a cover member 6l) having anges o6 and 67. may be fastened to the three side walls 51, 52 and 56. Disposed in the side wall 55 is a membrane 20 connected to a fluid conduit 22 which is used for a purpose to be described hereinbelow.

Referring now to Fig. 4, the double-armed toggle member of the electrical switching arrangement will be described. The toggle member contains outer wall portions 9 and it) and an inner U-shaped portion 11. Extending through the iiat walls 9 and 10 is a pin 12 which can be used for pivotally mounting the toggle member. A second pin 26 extends through an arm 0f the toggle member between the walls 9 and 10. The U-shaped portion 11 contains a recess 16 in the other arm of the toggle mmeber and has two U-shaped portions in which two actuating members 33 and 34 may be threadedly mounted.

The toggle member is pivotally mounted on the bottom of the housing 50. This can be best seen in Fig. 3 where the pin l2 is shown extending through the side portions 13 and 14 of a LJ-shaped stirrup 15. rhe stirrup .l5 may be welded to the bottom of the housing or otherwise fixedly connected thereto.

Also seen in Fig. 3 is a snap-acting switch element 36 having two longitudinal slits 37 and a central portion 35. As can be seen in Fig. 2 the central portion 3S is bowed out from the plane of the element 36 which is made of an electrically conductive material. The electrically conductive element 36 is mounted within an insulated yoke 45 having side portions 46 which are mounted in corresponding grooves in the side walls 5i. and 52 of the housing. Connections to the snap-acting element 36 are made by electrically-conductive bars 39 and 4E.. Conductors 29 can be attached to the bars 39 and 41 by means of screws 49.

Referring now to Figs. l and 2 it can be seen that the insulated yoke 4S is comparatively thin with respect to the width of the housing and is mounted within the U- shaped portion 11 of the toggle member so that the central portion 35 of the snap-acting member 36 is located between the actuating members 33 and 34. The members 33 and 34 may be adjusted so that they contact opposite sides of the central portion 35.

As seen in Fig. 2 the snap-acting element 36 is flxedly mounted at one of its ends to the bar 39 and has a movable contact 40 at its other end. The movable contact 4) is shown facing a mating fixed contact 42 which is mounted on the bar 41. From Fig. 2 it is clear how the conductors 29 enter the housing through the insulated tubes 43 and 44, respectively.

Referring now to Fig. l it can be seen that the recess 16 in one arm of the toggle member mates with a pointed plunger i8 connected to a disc 17 that is mounted on the membrane 20. It can be seen that the interior of the membrane is connected to the conduit 22 and it is apparent that the opposite end of the conduit 22 can be connected to a conventional temperature-responsive fluid container. Therefore, as the temperature of the fluid in this unillustrated uid container varies, the pressure exerted on the membrane 20 by the fluid varies in a predetermined manner. This causes the membrane to expand if the pressure increases or return to its unexpanded state if the pressure decreases.

Connected to the other arm of the double-armed toggle member, about the pin 26 thereof, is one end of a spring 24, the other end of which is connected to a lever 25 by means of a U-shaped bracket 27 and a screw 28. In Figs. 2 and 5 it can be seen that one end of the lever 25 It is self-evident how the cover 60 is xedly mounted in a groove 53 of the side wall 52 of the housing. The opposite interior end of the lever rests on the peripheral surface of a cam 30. The cam 3i) is mounted on one end of a rotatable shaft Si which extends through the side wall 51 of the housing and is rotatably mounted within the housing on a supporting member 47 having a groove 58 adapted to receive the inner end of the lever 25.

An additional adjustment is provided for the doublearmed toggle member by the resilient bracket 72 which mates with one end of the toggle member and can be adjusted by means of a screw 73. The means for mounting the member 47 and the bracket 72 can be seen clearly in Fig. 5.

In operation, the unillustrated end of the fluid conduit 22 is connected in the area whose temperature or pressure is to be controlled. The shaft 31 is initially adjusted by knob 32 to provide the desired stress in the spring 24. As the pressure within the membrane 2t) increases, the pointed plunger 1S moves to the left as seen in Figs. l and 2, tending to straighten the bowed element 35. At some predetermined position as the plunger i3 moves to the left, the snap-acting element 36 snaps into its second position so that the central portion is bowed in the opposite direction, causing the movable contact 40 to mate with the fixed contact 42 and place the switch in circuit-closed condition. It is clear that when the contact 4t) mates with the contact 42, electrical connection is made between the first conductor 29, the bar 39, the snap-acting element 36, the bar 41, and the other conductor 29.

Since the element 36 is a snap-acting element the contacts 46 and 42 will remain in their initial circuit-open condition until the snap action takes place. That is, the contacts are not continuously moved closer until they mate as is the case in a conventional switch arrangement. Therefore, there is no danger of voltage breakdown between the contacts before the predetermined position has been reached by the plunger 18.

The initial amount of rotation of the shaft 31 will determine the position of the cam 30 and in turn determine the initial force exerted by the spring 24 on the toggle member. This force is exerted on one arm of the toggle member in the upwards direction to the left of the pin 12 as shown in Fig. l and tends to keep the contacts 4@ and 42 in circuit-open position. Therefore, the larger the force exerted by the spring 24, the larger will be the force required to be exerted by the plunger I8 on the other end of the toggle member. In turn, this will require a larger pressure increase within the membrane 20.

In the event that it is desired to maintain the snapacting element in circuit-open position the pin 70 mounted on the cam 3i) can be utilized. In Fig. l it can be seen that the pin 70 rotates about the same center of rotation as the cam 30. Therefore, if the cam Sil is rotated counterclockwise as viewed in Fig. l the pin 70 will move to the right and bear up against the wall 9 of the toggle member. This will prevent the toggle member from being pivoted to the left about its pin 12 and will keep the switch in circuit-open condition regardless of the movement of the plunger 18.

In the arrangement shown in Figs. l and 2 the central portion 3S of the snap-acting element 36 is contacted by both actuating members 33 and 34 so that the snapping action is actually carried out by the outer arms of the element 36.

The described and illustrated switch arrangement is obviously light and compact and is capable of sustaining high current loads. It is particularly suitable for use in refrigerators and the like where the compressor unit must be energized and de-energized at certain time intervals depending on the temperature in a particular area of the refrigerator. The pins 70 have the circuit-opening function described hereinabove in this instance for defrosting purposes.

It will be vunderstood that each of the 'elements described above, or two or more together, may also find a useful application in other types of switching arrangements differing from the types described above.

While the invention has been illustrated and described as embodied in electrical switching arrangement including a snap-acting element, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

l. In an electrical switching arrangement, in combination, a housing including a U-shaped member having two facing side walls each of said side walls having parallel edges with respective rounded portions each of said side walls being formed with diametrically opposite grooves therein, a third side wall having parallel edges with respective rounded portions to slidably cooperate with said rounded edges of said facing side walls, a fourth side wall mounted on said U-shaped member facing said third side wall, said fourth side wall having rounded parallel edges adapted to slidably cooperate with said facing side walls of said U-shaped member, and a cover having a plurality of flange portions, each of said flange portions cooperating with one of said side walls; a toggle member having two arms and being pivotally mounted on said U-shaped member of said housing at a point between said arms thereof and turnable between two positions; a switch member mounted in said diametrically opposite grooves of said facing side walls of said housing and being movable between open and closed conditions, said switch member being operatively associated with a toggle arm of said toggle member so as to be moved by the same into one of its conditions when said toggle member is moved into one of its said positions and to be moved by the same into the other of said conditions when said toggle member is moved into the other of its said positions; operating means mounted on said third side wall and engaging one of said toggle arms of said toggle member for turning the same from'one of said positions to the other position thereof; and spring means mounted on said U-shaped member of said housing and engaging the other of said toggle arms of said toggle member and permanently tending to turn the same toward one position thereof.

2. In an electrical switching arrangement, in combination, a housing including a U-shaped member having two facing side walls each of said side walls having parallel edges with respective rounded portions each of said side walls being formed with diametrically opposite grooves therein, a third side wall having parallel edges with respective rounded portions to slidably cooperate with said rounded edges of said facing side walls, a fourth side wall mounted on said U-shaped member facing said third side wall, said fourth side wall having rounded parallel edges adapted to slidably cooperate with said facing side walls of said U-Shaped member, and a cover having a plurality of liange portions, each of said Hange portions cooperating with one of said side walls; a toggle member having two arms and being pivotally mounted on said U-shaped member of said housing at a point between said arms thereof and turnable between two positions; a switch member mounted in said diametrically opposite grooves of said facing side walls of said housing and being movable between open and closed conditions, said switch member vbeing operatively associated with a toggle arm of said toggle member so as to be moved by the same into one of its conditionswhen said toggle member is moved into one of its said positions and to be moved by the same into the other of said conditions when said toggle member is moved into the other of its said positions; operating means mounted on said third side wall and engaging one of said toggle arms of said toggle member for turning the same from one of said positions to the other position thereof; spring means mounted on said U-shaped member of said housing and engaging the other of said toggle arms of said toggle member and permanently tending to turn the same toward one position thereof; and adjusting means for adjusting said spring means for varying the tendency thereof for turning said toggle member towards said one position, said adjusting means being mounted on said U-shaped mem ber of said housing.

3. In an electrical switching arrangement, in combination, a housing; a flexible diaphragm mounted in one wall of said housing and having a pointed plunger; a double-armed bell crank lever pivotally mounted in said housing about an axis parallel to said diaphragm, one arm of said bell crank lever being bifurcated and having a recess therein; helical spring means mounted in said housing and arranged transversely to said plunger, said helical spring means engaging the second arm of said bell crank lever and permanently tending to turn said bifurcated arm towards said diaphragm and into engagement with said plunger; and a strip-like snap-acting switch member mounted in said housing within the recess of said bifurcated arm and adapted to be moved between operable positions thereof by said bifurcated arm.

4. In an electrical switching arrangement, in combination, a housing; a flexible diaphragm mounted in one wall of said housing and having a pointed plunger; a double-armed bell crank lever pivotally mounted in said housing about an axis parallel to said diaphragm, one arm of said bell crank lever being bifurcated and having a recess therein; helical spring means mounted in said housing and arranged transversely to said plunger, said helical spring means engaging the second arm of said bell crank lever and permanently tending to turn said bifurcated arm towards said diaphragm and into engagement with said plunger; an electrically insulating yoke member xedly mounted between two opposite walls of said housing and traversing said recess of said bifurcated lever arm and a strip-like snap-acting switch member mounted in said electrically insulating yoke and adapted to be moved between operable positions thereof by said bifurcated arm.

5. In an electrical switching arrangement, in combination, a housing; a switch actuating member pivotally mounted in said housing and turnable between two positions; a snap-acting switch member movable between open and closed positions and operatively connected to said switch actuating member so as to be moved by the same into one of said conditions when said switch actuating member is moved into lone of its said positions and to be moved into the other of its said conditions when said switch actuating member is moved into the other of its said positions; a flexible diaphragm mounted on a rst wall of said housing and adapted to be pressureactuated, said diaphragm having a portion thereof engaging said switch actuating member for turning the same from one of its said positions to the other of said positions thereof upon response to pressure actuation of said flexible diaphragm; spring means engaging said switch actuating member and permanently tending to turn the same towards one position thereof; a rotatable cam member mounted in a second wall of said housing perpendicular to said rst wall and extending through said second wall, said cam member thereby being adapted to be rotated from a point exterior of said housing, said cam member engaging said spring means and adapted upon rotation thereof to vary the tendency of said spring means for turning said switch actuating member towards said one position thereof; and limiting means mounted in said housing and engaging said switch actuating member to limit the movement of said switch actuating member by said spring means and said cam member to a predetermined amount.

References Cited in the file of this patent UNITED STATES PATENTS 1,066,215 Murray July 1, 1913 1,723,635 Tannehill Aug 6, 1929 2,013,435 Dobler et al. Sept. 3, 1935 2,044,736 Raney June 16, 1936 2,200,995 Procter May 14, 1940 2,242,769 Werner May 20, 1941 2,354,635 Harmon July 25, 1944 2,457,023 Zelt Dec. 21, 1948 2,466,522 Weber Apr. 5, 1949 2,598,536 Hansen May 27, 1952 

